A motor inside vacuum cleaner drives fan blades to rotate in high speed and draws air to move in pre-set direction to create pressure difference in an airflow channel and forms suction force, this suction force is guided to surface to be cleaned to pick up dust with help of different suction nozzles.
The suction nozzle is installed at the forefront of an extension pipe to be in direct contact with dust. Different kinds of suction nozzles are needed for best performance on different kinds of surfaces such as carpet, hard floor, sofa, crevice, etc., vacuum cleaners of different brands often supplied with different suction nozzles, and new suction nozzles are coming into market continuously, all of these make it necessary for some consumers to buy separate suction nozzle and thus have to consider fitting between the new suction nozzle and his vacuum cleaner.
The suction nozzle can connect with the extension pipe by outer fitting method and inner fitting method. In outer fitting method, the extension pipe is inserted into the outlet port part of suction nozzle, so it is important to make the outer part of the lower end of the extension pipe to be in the same shape and size as the internal part of the outlet port part. In inner fitting method, the suction nozzle is inserted into the extension pipe, it is important to make the outer part of the outlet port part to be in the same shape and size as the internal part of the extension pipe.
The most popular vacuum cleaner uses extension pipe with a circular internal air channel and φ32 mm outer diameter, for fitting suction nozzle with a circular air channel in the outlet port part and internal diameter is φ32 mm. This kind of suction nozzle is the most popular and thus the cheapest, it has all types for different vacuum cleaning task. Vacuum cleaner owners intends to buy a popular φ32 mm suction nozzle when necessary. If his extension pipe is not φ32 mm externally, or in different shape, he will need an adapter assembly.
The second popular vacuum cleaner uses the extension pipe with a circular internal air channel and a outer diameter of φ35 mm.
Internal shape of the extension pipe can be circular, oval, or even square, and circular is the most popular.
For circular extension pipe, the most popular outer diameter is φ32 mm, the 2nd popular is φ35 mm, and the 3rd popular is φ38 mm.
Some extension pipes have a locker to fit the suction nozzle, although most extension pipes do not have it.
Furthermore, in the competitive vacuum cleaner market, new brands are growing up continuously. Some new brands use suction nozzle with special shape or special size for certain function, or just for being unique. Some of these new brands are very successful in marketing, since they can only supply limited types of suction nozzle, consumer may need more suction nozzles for certain cleaning purpose after buying this kind of unique vacuum cleaners.
So it has been a concern of distributors to make their suction nozzles fit utmost vacuum types. The prevailing method is to supply several cylindrical short tubes together with suction nozzle, hoping at least one of these short tubes can meet consumer's requirement. Since only limited types of short tube can be supplied, and vacuum cleaner with new shape and new size is coming to market continuously, consumer can have difficulty in deciding which adapter or which suction nozzle can fit his vacuum cleaner. For example if his extension pipe is circular, he will have to decide what diameter of suction nozzle he needs, and choose from inner fitting method and outer fitting method. And, since only one of those adapting tubes will work in the final, consumer has to dispose other adapting tubes sent to him, this will be a waste to his money.
Patent file WO2013077793A1 Reservo tries to integrate different adapters to a single unit. The inventor of WO2013077793A1 realized the lower end of the extension pipe of the vacuum cleaner can be circular shape or non-circular, so he designed a detachable tube with non-circular outline in his invention and in the same shape as non-circular extension pipe of a certain vacuum cleaner. This detachable tube is nested in the non-circular internal channel of the adapter. If a consumer's vacuum cleaner happens to be with this specific non-circular size, he can simply take off the detachable tube of WO2013077793A1 Reservo and fit his extension pipe into the adapter. Since the detachable tube in WO2013077793A1 Reservo has circular internal channel with different diameter in different steps, for fitting the extension pipe with different outer diameter respectively, so the adapter disclosed by WO2013077793A1 Reservo can fit more than one vacuum cleaners. However, it can only fit limited pre-set vacuum types, if a vacuum cleaner is out of the pre-set size scope, this adapter will not work. And WO2013077793A1 Reservo can only fit extension pipe with smooth circular outline, if an extension pipe has locker projected out of its lower end, WO2013077793A1 Reservo will not work. So this is not a really universal adapter.